CN111747706A - Anti-cracking dry-mixed mortar and production process thereof - Google Patents

Abstract

The invention relates to an anti-cracking dry-mixed mortar and a production process thereof, belonging to the technical field of building materials, and the anti-cracking dry-mixed mortar comprises 450 parts of Portland cement 400-containing materials, 1450 parts of machine-made sand 1400-containing materials, 70-75 parts of fly ash, 30-90 parts of trilobal polypropylene fiber, 60-180 parts of brucite fiber, 30-60 parts of pure acrylic copolymer latex powder, 0.9-1.6 parts of cellulose ether and 6-12 parts of a high-efficiency naphthalene water reducer; a production process of anti-crack dry-mixed mortar comprises the following steps: s1: mixing brucite fiber and a high-efficiency naphthalene water reducing agent according to the weight part ratio to obtain a mixture; s2: and (4) uniformly mixing the mixture obtained in the step S1 with other components in parts by weight, and the invention has the effect of strong crack resistance.

Description

Anti-cracking dry-mixed mortar and production process thereof

Technical Field

The invention relates to the technical field of building materials, in particular to anti-cracking dry-mixed mortar.

Background

The dry-mixed mortar is a granular or powdery material which is prepared by physically mixing dry-screened aggregate, inorganic cementing material (cement), additive and the like according to a certain proportion, is transported to a construction site in a bag or in bulk form, and can be directly used after being mixed with water.

The prior Chinese patent with the reference public number of CN105294013A discloses dry-mixed masonry mortar, which is characterized in that: the composite material comprises the following components in percentage by mass: 70.2 to 80 percent of machine-made sand; 9 to 20 percent of cement; 1% -11% of fly ash; 0.1-0.8% of an additive, wherein the additive comprises a modifier and a thickening agent, the modifier is a mixture of starch ether, polysiloxane and polycarboxylic acid, the thickening agent is vinyl acetate homopolymerized rubber powder, and the weight ratio of the vinyl acetate homopolymerized rubber powder to the starch ether to the polysiloxane to the polycarboxylic acid is vinyl acetate homopolymerized rubber powder: starch ether: polysiloxane: and polycarboxylic acid =100:1.6:14.5: 4.8.

The above prior art solutions have the following drawbacks: the mortar is accompanied with the increase of various shrinkage (such as chemical shrinkage, temperature shrinkage, plastic shrinkage, dry shrinkage, self-shrinkage and the like) in the hardening process, so that the mortar generates a plurality of micro cracks, and the increase of the cracks can seriously affect the engineering quality and the normal use of the engineering.

Disclosure of Invention

The invention aims to provide dry-mixed mortar with strong crack resistance.

The first object of the present invention is achieved by the following technical solutions:

the anti-crack dry-mixed mortar comprises the following components: 450 parts of Portland cement, 1400 parts of machine-made sand, 1450 parts of fly ash, 70-75 parts of trefoil polypropylene fiber, 60-180 parts of brucite fiber, 30-60 parts of pure acrylic copolymer latex powder, 0.9-1.6 parts of cellulose ether and 6-12 parts of high-efficiency naphthalene water reducing agent.

By adopting the technical scheme, the fibers are distributed in the mortar in a disorderly manner to form a three-dimensional network structure, the generation and development of microcracks are controlled by pulling out the energy action and the bridging action, the mechanical property of the mortar is enhanced, cracks are generated due to dehydration shrinkage in the hardening process of the portland cement mortar, when the fibers are doped into the mortar, the development of crack tips is limited, the cracks can only bypass the fibers or stretch the fibers to continue to develop, so that huge energy is consumed to overcome the limiting action of the fibers on the development of the cracks, and the generation of the cracks in the mortar is effectively prevented.

The trilobal polypropylene fiber is obtained by performing special spinning production process and surface treatment on polypropylene fiber, the cross section of the trilobal polypropylene fiber is a trilobal special-shaped cross section, the specific surface area of the fiber is greatly increased, so that the contact area of the fiber and a mortar matrix material is increased, the bond strength is improved, the special surface treatment process enables the surface of the trilobal polypropylene fiber to form an organism which is mainly chemically adsorbed and is secondarily adsorbed, so that the bonding force between the fiber and the mortar matrix is enhanced, the trilobal polypropylene fiber has better dispersibility, and the crack resistance of mortar is favorably improved; the brucite fiber is formed under the condition of an alkaline medium, is an alkaline mineral with simple components, has good alkali resistance, good stability in strong alkali, the loss of alkali is about 2 percent, the brucite fiber and Portland cement have good compatibility and bonding strength, and the unique OH group of the brucite fiber also makes the brucite fiber possibly react with calcium silicate generated by hydration of the Portland cement to form silicon hydroxyl so as to obviously improve the bonding property of the fiber and the Portland cement base material, really plays a role of the fiber in mortar and overcomes the defect of poor interface bonding of the fiber and the Portland cement base material in the prior art; the trilobal polypropylene fibers and the brucite fibers can be mutually cooperated to play a role in connection, so that the cracking resistance and the toughness of the prepared mortar are better improved.

The method is characterized in that a frame system composed of inorganic and organic adhesives is formed in the solidified mortar along with the formation of a final polymer film of pure acrylic copolymer latex powder in the anti-crack mortar, the pure acrylic copolymer latex powder forms flexible connection with a film formed on the solid surface in the gap of a brittle framework composed of a hydraulic material, so that the strength of the mortar is enhanced, the cohesive force is improved, the deformability of the mortar is improved because the flexibility of the polymer is far higher than that of a rigid structure formed by silicate cement and the like, the deformability of the mortar is improved because the deformability of the polymer is far higher than that of the rigid structure formed by silicate cement and the like, and the action of dispersed stress is greatly improved, thereby improving the anti-crack capability of the mortar; the pure acrylic copolymer latex powder particles can be uniformly adsorbed outside the trilobal polypropylene fibers, the water content is gradually reduced along with the hydration and the evaporation of water, the pure acrylic copolymer latex powder forms a polymer film, the trilobal polypropylene fibers can be well combined with the polymer film, and the trilobal polypropylene fibers have good binding force with mortar due to good adsorption capacity of the trilobal polypropylene fibers, so that the trilobal polypropylene fibers and the pure acrylic copolymer latex powder are compounded, and the crack resistance of the dry-mixed mortar is better; the trilobal polypropylene fiber and the brucite fiber exist in a frame system formed by inorganic and organic adhesives, so that the connection strength of the frame system is further enhanced, and the crack resistance of the dry-mixed mortar is favorably improved.

When the cellulose ether is added into the mortar, hydroxyl groups on the structure of the cellulose ether and oxygen atoms on ether bonds are associated with water molecules to form hydrogen bonds to form a space network, so that free water is changed into bound water, a good water retention effect is achieved, the mortar can be prevented from being isolated and bleeding, and the water can be prevented from being evaporated too fast or absorbed too fast by a base material at the initial stage of maintenance, so that the portland cement can be hydrated well, the bonding strength between the mortar and the base material can be improved, the compression-fracture ratio of the dry-mixed mortar is reduced by adding the cellulose ether, the flexibility of the mortar is improved, and the mortar is not easy to crack; the pure acrylic copolymer latex powder forms a latex film when meeting water, the latex film loses water in a dry environment to cause the shrinkage of the latex film, cellulose ether is dispersed in water to fill the pores of cement, the resistance of water diffusion is increased, the conversion between carbonyl and polyhydric alcohol in the pure acrylic copolymer latex powder is influenced, the water loss of the latex film is reduced, the latex film keeps flexibility, and the anti-cracking performance of mortar is favorably enhanced.

The silicate cement can form a flocculation structure in the hydration process, wrap free water and reduce the workability of the silicate cement, the molecules of the doped high-efficiency naphthalene water reducing agent are adsorbed on the surface of the flocculation structure, the whole flocculation structure is charged like the charges due to the ionization of polar hydrophilic groups, and the flocculation particles are mutually repelled due to the same charges, so that the flocculation structure is destroyed, the wrapped free water is released, the lubrication effect among the silicate cement particles is enhanced, the workability of the silicate cement is improved on the basis of not increasing the water consumption, and the performance of dry-mixed mortar is improved; the efficient naphthalene water reducer is an anionic surfactant and contains a large number of hydrophilic group sulfonic groups, after the efficient naphthalene water reducer is dissolved in water, hydrophilic groups are dispersed, the surface tension of medium water and the contact angle of water on the surface of brucite fibers can be reduced, so that the brucite fibers are sufficiently wetted, meanwhile, the efficient naphthalene water reducer reduces the surface activity of the brucite fibers, the efficient naphthalene water reducer is uniformly adsorbed on the surface of the brucite fibers to form a lubricating film, the friction force among the brucite fibers is reduced, the chance of mutual adhesion among the brucite fibers is reduced, collision agglomeration and gravity precipitation caused by mutual friction of the brucite fibers are prevented, the brucite fibers are better dispersed and uniformly distributed in mortar, and the dry mixing resistance of the mortar is favorably improved.

The invention is further configured to: the weight ratio of the trilobal polypropylene fiber to the brucite fiber is 1 (1.5-3).

By adopting the technical scheme, in the proportion range, the trilobal polypropylene fiber and brucite fiber have better matching effect, and the dry-mixed mortar has better crack resistance.

The invention is further configured to: the trilobal polypropylene fiber comprises long fibers and short fibers, wherein the length of the long fibers is 1.4mm, the length of the short fibers is 0.9mm, and the weight ratio of the long fibers to the short fibers is 1 (1-3).

By adopting the technical scheme, the fibers with the length of not more than 1.4mm are not easy to tangle and knot in the manufacturing process, and are also easy to stir and disperse in the dispersing process, so that the fibers are split into single fibers in the nanometer level, and the single fibers in the nanometer level are uniformly distributed in the mortar to form net distribution, thereby effectively preventing the growth of microcracks in the mortar and playing a role in cracking resistance; the long fibers are distributed in the mortar in a random manner to form a three-dimensional network structure, the short fibers are also distributed in the mortar in a random manner, and the short fibers can be distributed in a random manner to fill the gaps of the three-dimensional network structure formed by the long fibers, so that the three-dimensional network structure in the mortar is filled more tightly, the development of crack tips can be more fully prevented, and the crack resistance of the dry-mixed mortar is favorably enhanced.

The invention is further configured to: the brucite fiber comprises long fibers and short fibers, the length of the long fibers is 1.4mm, the length of the short fibers is 0.9mm, and the weight ratio of the long fibers to the short fibers is 1 (1-3).

The invention is further configured to: the weight ratio of the pure acrylic copolymer latex powder to the cellulose ether is (30-40): 1.

by adopting the technical scheme, in the proportion range, the cellulose ether can play a good role in water retention and thickening and can be well matched with the pure acrylic copolymer latex powder, so that the flexibility of a copolymer latex film formed by the pure acrylic copolymer latex powder is ensured, and the crack resistance of the dry-mixed mortar is enhanced.

The invention is further configured to: the weight ratio of the brucite fiber to the high-efficiency naphthalene water reducing agent is (10-15): 1.

by adopting the technical scheme, in the proportion range, the high-efficiency naphthalene water reducing agent can improve the workability of portland cement and achieve a good dispersing effect on brucite fibers, so that the brucite fibers are independent and distributed in mortar as single fibers, and the anti-cracking performance of the mortar is favorably improved.

The invention is further configured to: the anti-cracking mortar also comprises 0.8-1.0 part of polyol defoaming agent.

By adopting the technical scheme, in the process of adding water and mixing the dry-mixed mortar, air is brought into the fresh-mixed mortar and is wrapped by the wet mortar to form air bubbles, in addition, chemical additives such as pure acrylic copolymer latex powder, cellulose ether and the like have hydrophilic groups, so that the surface tension of liquid can be reduced, foam aggregation is induced, after the defoaming agent in the dry-mixed mortar is dissolved in water, defoaming solution with lower surface tension is generated and is attached to the liquid film, defoaming agent molecules adsorbed on the liquid film replace surface active molecules for stabilizing bubbles, so that the local surface energy of the liquid film is reduced, the film with poor strength is formed, liquid adjacent under the liquid film is taken away while the liquid film is thinned, the liquid film is broken, the reduction of bubbles is favorable for enhancing the bonding strength of mortar, in addition, the defoaming agent can reduce the later-stage compression-fracture ratio of the mortar, improve the flexibility of the mortar and enable the mortar to be difficult to crack.

The invention also aims to provide a production process of the anti-crack dry-mixed mortar, which comprises the following steps:

s1: mixing brucite fiber and a high-efficiency naphthalene water reducing agent according to the weight part ratio to obtain a mixture;

s2: and (4) uniformly mixing the mixture obtained in the step S1 with other components in parts by weight.

By adopting the technical scheme, the brucite fiber and the high-efficiency naphthalene water reducing agent are mixed firstly, so that the high-efficiency naphthalene water reducing agent can act on the brucite fiber more fully, the dispersing effect of the high-efficiency naphthalene water reducing agent on the brucite fiber is exerted to the maximum, then the mixture of the high-efficiency naphthalene water reducing agent and the brucite fiber is mixed with other components to prepare the dry-mixed mortar, the brucite fiber is uniformly distributed in the mortar as a single independent fiber to form a net structure, and the anti-cracking performance of the dry-mixed mortar is improved.

In conclusion, the beneficial technical effects of the invention are as follows:

1. the trilobal polypropylene fibers and the brucite fibers are mutually cooperated to play a role in connection, so that the cracking resistance and the toughness of the prepared mortar are better improved;

2. the trilobal polypropylene fiber, the brucite fiber and the pure acrylic copolymer latex powder are matched together, so that the connection strength of a polymer latex film generated by the pure acrylic copolymer latex powder, cement and machine-made sand is enhanced, and the crack resistance of the dry-mixed mortar is favorably improved;

3. the long fibers and the short fibers are distributed disorderly in the dry-mixed mortar to form a tighter spatial network structure, so that the growth of microcracks in the mortar is effectively prevented, and the crack resistance effect is achieved.

Detailed Description

The raw materials used in the examples are commercially available, wherein the manufactured sand product number is DZLL 2006-15 from Shijiazhuangdze mineral products Ltd, P.O32.5 ordinary portland cement from Lingshou county Yuntong mineral product processing factory, first grade fly ash from Lingshou county Yuntong mineral product processing factory, 1.4mm trilobal polypropylene fiber from Yuxue City Yuyu engineering fiber Ltd, 0.9mm trilobal polypropylene fiber from Yuxue City Yuyu engineering fiber Ltd, 1.4mm brucite fiber from Boshan mineral product processing factory in Lingshou county, 0.9mm brucite fiber from Boshan mineral product processing factory in Showa county, pure acrylic acid can be purchased from Kyowa Kao Kagawa chemical industry Co., Ltd at a dispersed latex powder number of DH-3001, hydroxypropyl methyl cellulose HPMC from Shandongxin Biochemical engineering technology Ltd, Nagaku high efficiency chemical industry Co., Zhengzheng city, polyol defoamer model number GP330 was purchased from santa chemical (southwest) ltd.

Example 1

An anti-crack dry-mixed mortar comprises the following components: 400kg of Portland cement, 1500kg of machine-made sand, 70kg of fly ash, 90kg of trilobal polypropylene fiber, 60kg of brucite fiber, 60kg of pure acrylic copolymer latex powder, 1.6kg of cellulose ether and 6kg of high-efficiency naphthalene water reducing agent.

Wherein, the trilobal polypropylene fiber contains 30kg of long fiber and 60kg of short fiber, and the brucite fiber contains 20kg of long fiber and 40kg of short fiber.

A production process of anti-crack dry-mixed mortar comprises the following steps:

s1: mixing brucite fiber with a high-efficiency naphthalene water reducing agent to obtain a mixture;

s2: and (4) uniformly mixing the mixture obtained in the step S1 with other components.

Example 2

The difference from the embodiment 1 is that: an anti-crack dry-mixed mortar comprises the following components: 425kg of Portland cement, 1450kg of machine-made sand, 74kg of fly ash, 60kg of trilobal polypropylene fiber, 120kg of brucite fiber, 45kg of pure acrylic copolymer latex powder, 1.3kg of cellulose ether and 9kg of high-efficiency naphthalene water reducing agent.

Wherein, the trilobal polypropylene fiber comprises 20kg of long fiber and 40kg of short fiber, and the brucite fiber comprises 40kg of long fiber and 80kg of short fiber.

Example 3

The difference from the embodiment 1 is that: the anti-crack dry-mixed mortar comprises the following components: 450kg of Portland cement, 1400kg of machine-made sand, 78kg of fly ash, 30kg of trilobal polypropylene fiber, 180kg of brucite fiber, 30kg of pure acrylic copolymer latex powder, 1.6kg of cellulose ether and 12kg of high-efficiency naphthalene water reducing agent.

Wherein, the trilobal polypropylene fiber comprises 10kg of long fiber and 20kg of short fiber, and the brucite fiber comprises 60kg of long fiber and 120kg of short fiber.

Example 4

The difference from example 2 is: the amount of brucite fiber was 90 kg.

Example 5

The difference from example 2 is: the trilobal polypropylene fiber was 40 kg.

Example 6

The difference from example 2 is: the trilobal polypropylene fibers contained 30kg of long fibers and 30kg of short fibers.

Example 7

The difference from example 2 is: the trilobal polypropylene fiber had 15kg of long fibers and 45kg of short fibers.

Example 8

The difference from example 2 is: the brucite fiber contains 60kg of long fibers and 60kg of short fibers.

Example 9

The difference from example 2 is: the brucite fiber contains 30kg of long fibers and 90kg of short fibers.

Example 10

The difference from example 2 is: the pure acrylic copolymer latex powder is 39 kg.

Example 11

The difference from example 2 is: the pure acrylic copolymer latex powder is 52 kg.

Example 12

The difference from example 2 is: the high-efficiency naphthalene water reducing agent is 12 kg.

Example 13

The difference from example 2 is: the high-efficiency naphthalene water reducing agent is 8 kg.

Example 14

The difference from example 2 is: also included is 0.8kg of a polyol defoamer.

Example 15

The difference from example 2 is: also included is 0.9kg of a polyol defoamer.

Example 16

The difference from example 2 is: also included is 1kg of a polyol defoamer.

Comparative example 1

The difference from example 2 is: 120kg of brucite fibres were replaced by 120kg of trilobal polypropylene fibres.

Comparative example 2

The difference from example 2 is: 60kg of trilobal polypropylene fibres were replaced by 60kg of brucite fibres.

Comparative example 3

In contrast to example 2: the amount of brucite fiber was 60 kg.

Comparative example 4

The difference from example 2 is: 240kg of brucite fiber.

Comparative example 5

The difference from example 2 is: the trilobal polypropylene fibers contained 40kg of long fibers and 20kg of short fibers.

Comparative example 6

The difference from example 2 is: the trilobal polypropylene fibers contained 12kg of long fibers and 48kg of short fibers.

Comparative example 7

The difference from example 2 is: the brucite fiber contains 80kg of long fibers and 40kg of short fibers.

Comparative example 8

The difference from example 2 is: the brucite fiber contains 24kg of long fibers and 96kg of short fibers.

Comparative example 9

The difference from example 2 is: the production process of the anti-crack dry-mixed mortar comprises the following steps: all components were mixed well.

Comparative example 10

CN107365127B discloses a dry-mixed masonry mortar.

Performance detection

And (3) testing and measuring the breaking strength, the compressive strength and the bonding strength of the dry-mixed mortar according to a test method for physical properties of the dry-mixed mortar GB/T29756 and 2013.

TABLE 1 Performance test results

As can be seen from Table 1, the experimental data of examples 1 to 16 and comparative example 10 show that the dry-mixed mortars obtained in examples 1 to 16 have better 28d flexural strength than comparative example 10, and the dry-mixed mortars obtained in examples 1 to 16 have better crack resistance, which indicates that the dry-mixed mortars of the invention have better component ratios and better production process.

The dry-mixed mortars prepared in examples 1 to 3 all have better crack resistance, wherein the dry-mixed mortar prepared in example 2 has the best crack resistance, which shows that the dry-mixed mortar obtained in example 2 has better component proportion and production process.

The experimental data of comparative example 2 and comparative examples 1-2 show that the crack resistance of the dry-mixed mortar is better than that of the dry-mixed mortar added with the trilobal polypropylene fiber and the brucite fiber, which indicates that the trilobal polypropylene fiber and the brucite fiber have synergistic effect in the dry-mixed mortar to improve the crack resistance of the dry-mixed mortar.

Comparing the data of examples 2, 4 and 5 with those of comparative examples 3 to 4, it was found that the dry-mixed mortar obtained when the weight ratio of the polypropylene trilobal fibers to the brucite fibers was in the range of 1 (1.5 to 3) was more excellent in crack resistance.

Comparing the data of examples 2, 6 and 7 with those of comparative examples 5 to 6, it was found that the dry-mixed mortar obtained with the trilobal polypropylene fibers having a weight ratio of long fibers to short fibers in the range of 1 (1-3) was more excellent in crack resistance.

Comparing the data of examples 2, 8 and 9 with those of comparative examples 7 to 8, it was found that the dry-mixed mortar obtained with the brucite fibers having a weight ratio of long fibers to short fibers in the range of 1 (1-3) was more excellent in crack resistance.

Comparing the data of examples 2, 10, 11, it was found that the weight ratio of the pure acrylic copolymer latex powder to the cellulose ether was 34.6: 1, the prepared dry-mixed mortar has better crack resistance.

Comparing the data of examples 2, 12 and 13, the weight ratio of the brucite fibers to the high-efficiency naphthalene water reducing agent is 13.3: 1, the prepared dry-mixed mortar has better crack resistance.

Comparing the data of examples 2, 14, 15 and 16, it is found that the anti-cracking performance of the dry-mixed mortar is improved by adding the polyol defoamer, the bonding performance of the dry-mixed mortar is better by adding the polyol defoamer, the anti-cracking performance and the bonding performance of the dry-mixed mortar prepared in example 15 are better, and the component proportion and the production process of the dry-mixed mortar prepared in example 15 are optimal.

Comparing the data of example 2 with that of comparative example 9, it was found that the crack resistance of the dry-mixed mortar prepared by mixing the brucite fibers with the naphthalene based water reducer and then mixing the mixture of the brucite fibers and the naphthalene based water reducer with the other components was stronger than that of the dry-mixed mortar prepared by directly mixing all the components at the same time.

The above-mentioned embodiments are merely illustrative and not restrictive, and those skilled in the art can modify the embodiments without inventive contribution as required after reading this specification, but only fall within the scope of the claims of the present invention.

Claims (8)

1. An anti-crack dry-mixed mortar is characterized in that: the paint comprises the following components in parts by weight: 450 parts of Portland cement, 1400 parts of machine-made sand, 1450 parts of fly ash, 70-75 parts of trefoil polypropylene fiber, 60-180 parts of brucite fiber, 30-60 parts of pure acrylic copolymer latex powder, 0.9-1.6 parts of cellulose ether and 6-12 parts of high-efficiency naphthalene water reducing agent.

2. The crack-resistant dry-mixed mortar of claim 1, wherein: the weight ratio of the trilobal polypropylene fiber to the brucite fiber is 1 (1.5-3).

3. The crack-resistant dry-mixed mortar of claim 1, wherein: the trilobal polypropylene fiber comprises long fibers and short fibers, wherein the length of the long fibers is 1.4mm, the length of the short fibers is 0.9mm, and the weight ratio of the long fibers to the short fibers is 1 (1-3).

4. The crack-resistant dry-mixed mortar of claim 1, wherein: the brucite fiber comprises long fibers and short fibers, the length of the long fibers is 1.4mm, the length of the short fibers is 0.9mm, and the weight ratio of the long fibers to the short fibers is 1 (1-3).

5. The crack-resistant dry-mixed mortar of claim 1, wherein: the weight ratio of the pure acrylic copolymer latex powder to the cellulose ether is (30-40): 1.

6. the crack-resistant dry-mixed mortar of claim 1, wherein: the weight ratio of the brucite fiber to the high-efficiency naphthalene water reducing agent is (10-15): 1.

7. the crack-resistant dry-mixed mortar of claim 1, wherein: the anti-cracking mortar also comprises 0.8-1.0 part of polyol defoaming agent.

8. The process for producing an anti-crack dry-mixed mortar according to any one of claims 1 to 7, comprising the steps of:

s1: mixing brucite fiber and a high-efficiency naphthalene water reducing agent according to the weight part ratio to obtain a mixture;

s2: and (4) uniformly mixing the mixture obtained in the step S1 with other components in parts by weight.